NGC 1808
Galaxy in the constellation Columba
From Wikipedia, the free encyclopedia
NGC 1808 is a barred spiral galaxy[3] located in the southern constellation of Columba, about two degrees to the south and east of Gamma Caeli.[1] It was discovered on 10 May 1826 by Scottish astronomer James Dunlop, who described it as a "faint nebula".[8][9] The galaxy is a member of the NGC 1808 group, which is part of the larger Dorado Group.[8]
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| NGC 1808 | |
|---|---|
NGC 1808 imaged by the Cerro Tololo Inter-American Observatory | |
| Observation data (J2000 epoch) | |
| Constellation | Columba[1] |
| Right ascension | 05h 07m 42.331s[2] |
| Declination | −37° 30′ 45.88″[2] |
| Redshift | 0.003339[2] |
| Distance | 41.7 ± 3.9 Mly (12.8 ± 1.2 Mpc)[3] |
| Group or cluster | Dorado Group |
| Apparent magnitude (V) | 9.94[4] |
| Apparent magnitude (B) | 10.83[5] |
| Characteristics | |
| Type | (R)SAB(s)a[6] |
| Size | ~88,100 ly (27.01 kpc) (estimated)[2] |
| Apparent size (V) | 7′.41 × 3′.39[7] |
| Other designations | |
| ESO 305- G 008, IRAS 05059-3734, MCG -06-12-005, PGC 16779[2] | |
The morphological classification of this galaxy is (R)SAB(s)a,[6] which indicates a spiral galaxy with a weak-bar around the nucleus (SAB), no ring around the bar (s), an outer ring (R), and tightly-wound spiral arms (a). It is inclined by an angle of 57° to the line of sight from the Earth, with the long axis oriented at a position angle of 324°.[3] The disk of gas and stars shows a noticeable warp, and there is a pronounced asymmetry in the distribution of neutral hydrogen and H II regions.[10]
The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing star clusters and supernova remnants at a distance of ~280 pc from the center. These form a ring of peculiar "hot spots".[11] It was formerly identified as a possible Seyfert galaxy,[3] but evidence now points to starburst activity in a ~500 pc radius around the center.[12] A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes.[3] The high level of star formation in this galaxy and the nearby NGC 1792 may indicate a recent, distant tidal interaction between the two.[10]
One supernova has been observed in NGC 1808: SN 1993af (type Ia, mag. 17) was discovered by Marina Wischnjewsky on 15 November 1993 at 220″ east and 94″ north of the galactic nucleus.[13][14][15]
